Certain friction-welding devices are conventional. One distinguishing criterion is the utilized kinematical principle. In the case at hand, devices are involved in which one of two components to be joined is held statically, the other is moved in an oscillating manner, i.e., periodically moved back and forth, and is pressed against the static component in the process. The periodic movement occurs parallel to the provided welding surfaces and is generated by a so-called oscillator. The pressing occurs perpendicular to the welding surfaces with the aid of a suitable compression device. Due to the high compression and friction forces, the usually smaller, moved component is retained in a sturdy cartridge that leaves only the welding zone accessible in most cases. The oscillatory movement may be implemented on a straight and/or curved path, for instance on a portion of a circular arc. In the straight-line variant, the designation “linear friction welding”, abbreviated LFW, is often used. In view of the high dynamic stresses, all elements of a friction-welding device must be designed as especially robust and dimensionally stable elements which are free from play, which applies especially when larger components made of high-strength metals are welded. Also important are precise, reproducible and variable friction and compression movements with high positioning accuracy at the end of the dynamic friction process. All of these criteria, after years of development, have had the result that mechanical and hydraulic variants as well as combinations of the two have become accepted for the direct generation of the required forces and motions. It is understood that the corresponding drives also include electromotors, electronic open-loop and closed-loop controls, i.e., electrical and electronic elements.
European Published Patent Application No. 0 513 669 describes a friction-welding method for the blading of a blade carrier for turbo engines together with the required device and device elements. The actual implementation of this friction-welding device operates with the aid of an electromotorically driven, mechanical oscillator according to an eccentric principle, as well as with an electro-hydraulic, pressurized hydraulic compression device.
In mechanical oscillators the maximum movement frequency is limited to values below 100 Hertz (Hz). In hydraulic oscillators the maximum frequency is above 100 Hz but still below 150 Hz. According to the equation power—force×velocity, the friction power is proportional to the friction force, the movement amplitude and the movement frequency. The friction force results from the normal force and the coefficient of friction. At a predefined amplitude, predefined frequency (cf. above maximum values) and predefined coefficient of friction, the friction power can be increased or influenced only via the normal force/pressure force. At a predefined friction power, the relative low frequencies of the mechanical and hydraulic oscillators result in correspondingly high contact pressures that have to be generated by the compression device. High forces require mechanically especially robust and massive, i.e., heavy, components for the friction-welding device.